Adaptive power modulation

ABSTRACT

A system may comprise a sensor device. The sensor device may be configured to determine a received signal strength indicator (RSSI) of a signal received from another device. The sensor device may be configured to determine, based on the RSSI and a sensitivity threshold, a transmission power level. The sensor device may be configured to send a second signal using the determined transmission power level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/828,072, filed Nov. 30, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/215,227, filed Mar. 17, 2014, issued as U.S.Pat. No. 9,867,143 on Jan. 9, 2018, which claims the benefit of U.S.Patent Application No. 61/788,715, filed Mar. 15, 2013.

BACKGROUND

There are numerous conventional battery powered wireless devicesavailable, and these devices have a fixed transmit power and includebatteries typically sized for a year or two of operation. Thesebatteries, for example, include small lithium batteries, such as theCR2, CR123 or CR2032 coin cell batteries. Since transmit power candegrade as battery capacity diminishes, the effective range of thewireless link is also affected. As such, the device is effectively deadwhen the range of the device is adversely affected by the battery life,even though there is capacity remaining in the battery. In a securitysystem, any degradation of the system can leave the system in avulnerable state, such as a particular zone may now be unable to detectan intrusion. Thus, there is a need for adaptive power modulation tooptimize battery life in host systems.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a flow diagram of example adaptive power modulation.

SUMMARY

Systems and methods for adaptive power modulation are disclosed. As anexample, a received signal strength indicator (RSSI) of a signal may bedetermined. Based on the RSSI and a sensitivity threshold, atransmission power level may be determined. For example, it may bedetermined that the RSSI exceeds a sensitivity threshold of a receiverof a device. As another example, the transmission power level may bedetermined based on a difference between the RSSI and the sensitivitythreshold. The determined transmission power level may be used to sendanother signal. The transmission power level may be used to adjust atransmitter of the sensor device.

DETAILED DESCRIPTION

Although the detailed description herein contains many specifics for thepurposes of illustration, anyone of ordinary skill in the art willappreciate that many variations and alterations to the following detailsare within the scope of the embodiments described herein. Thus, thefollowing illustrative embodiments are set forth without any loss ofgenerality to, and without imposing limitations upon, the claimedinvention.

FIG. 1 is a flow diagram of adaptive power modulation 100, under anembodiment. Systems and methods comprise determining a received signalstrength (RSSI) of a signal 102. A sensitivity level of a receiver isdetermined 104, where the signal is to be received at the receiver. Whena determination is made that the RSSI is greater than the sensitivitylevel, a transmitter power level is calculated as a difference betweenthe RSSI and the sensitivity level 106. A transmitter of the signal iscontrolled in accordance with the transmitter power level 108.

Wireless range is given by the Friis' equation asP _(r) =P _(t) *G _(t) *G _(r)*losswhere the variable P_(t) represents transmit power, the variable P_(r)represents receiver power, the variable G_(r) represents receiverantenna gain, and the variable G_(t) represents transmitter antennagain. Assuming a fixed range for any given wireless sensor (i.e., thesensor is fixed in space, and not moving), then some sensors will havemore than adequate receive power. For example, a device has 100 mWtransmit power (20 dBm), the antenna gains are both 2 dBi, receiversensitivity is −100 dBm and the distance is 20 m. To accommodate humanbody absorption, the example allows 15 dBm as margin in the system. Thismeans the minimum RSSI for the link should be approximately equivalentto the receiver sensitivity adjusted for the absorption (e.g., −85 dBm).If the sensor is placed only 10 m away, then the receiver is seeing muchmore power than required to obtain and recover the communications. Thismeans current being used by the power amplifier (PA) and low noiseamplifier (LNA) is being wasted, thus also wasting battery life.

Upon sensor pairing, i.e. a method of connecting two wireless devices,say as used in Zigbee communication protocol, the two devicescommunicate on each packet, both the received signal strength (RSSI) ofthe other devices(s) in the communication system. If the RSSI is greaterthan the sensitivity level (e.g., −80 dBm (allowing approximately 5 dBmfor signal to noise ratio)), then the difference between the RSSIreceived and the sensitivity level (e.g., −80 dBm) is the amount ofpower being wasted for that link. So the amount of power reduction usingthe adaptive power modulation of an embodiment, and thus amount ofbattery capacity that can be saved, is the difference, on apacket-to-packet basis, between the RSSI and the sensitivity level(e.g., −80 dBm).

Therefore, using the example described herein, if the RSSI is −60 dBm,then the amount of power difference is 20 dBm. If that transmitter isoriginally putting out 20 dBm, it could be reduced to 0 dBm to achievethe same communication link range for that particular sensor and saveapproximately 99 mW of power.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in a sense of “including,but not limited to.” Words using the singular or plural number alsoinclude the plural or singular number respectively. Additionally, thewords “herein,” “hereunder,” “above,” “below,” and words of similarimport, when used in this application, refer to this application as awhole and not to any particular portions of this application. When theword “or” is used in reference to a list of two or more items, that wordcovers all of the following interpretations of the word: any of theitems in the list, all of the items in the list and any combination ofthe items in the list.

The above description of embodiments and corresponding systems andmethods is not intended to be exhaustive or to limit the systems andmethods to the precise forms disclosed. While specific embodiments of,and examples for, the systems and methods are described herein forillustrative purposes, various equivalent modifications are possiblewithin the scope of the systems and methods, as those skilled in therelevant art will recognize. The teachings of the systems and methodsprovided herein can be applied to other systems and methods, not onlyfor the systems and methods described above.

The elements and acts of the various embodiments described above can becombined to provide further embodiments. These and other changes can bemade to the embodiments and corresponding systems and methods in lightof the above detailed description.

In general, in the following claims, the terms used should not beconstrued to limit the invention and corresponding systems and methodsto the specific embodiments disclosed in the specification and theclaims, but should be construed to include all systems that operateunder the claims. Accordingly, the invention and corresponding systemsand methods is not limited by the disclosure, but instead the scope isto be determined entirely by the claims.

While certain aspects of the systems and methods are presented below incertain claim forms, the inventors contemplate the various aspects ofthe systems and methods in any number of claim forms. Accordingly, theinventors reserve the right to add additional claims after filing theapplication to pursue such additional claim forms for other aspects ofthe systems and methods described herein.

The invention claimed is:
 1. A method comprising: determining a receivedsignal strength indicator (RSSI) of a first signal from a first deviceto a second device; determining, based on the RSSI exceeding asensitivity threshold of the second device, a transmission power level;and causing sending of a second signal using the transmission powerlevel.
 2. The method of claim 1, wherein the determining the RSSI of thefirst signal comprises determining the RSSI of the first signal by athird device.
 3. The method of claim 1, wherein the determining thetransmission power level comprises determining the transmission powerlevel by a third device.
 4. The method of claim 1, wherein the causingsending of the second signal comprises causing, by a third device, thesending of the second signal.
 5. The method of claim 1, wherein thedetermining the RSSI of the first signal comprises determining the RSSIof the first signal by the second device.
 6. The method of claim 1,wherein the determining the transmission power level comprisesdetermining the transmission power level by the second device.
 7. Themethod of claim 1, wherein the causing sending of the second signalcomprises causing, by the second device, the sending of the secondsignal.
 8. The method of claim 1, wherein the sensitivity threshold ofthe second device comprises a minimum signal strength that the seconddevice is configured to receive.
 9. The method of claim 1, wherein thecausing the sending of the second signal comprises sending, to at leastone of the first device or the second device, an indication to modify atransmission power of the at least one of the first device or the seconddevice.
 10. A first device comprising: one or more processors; andmemory storing instructions that, when executed by the one or moreprocessors, cause the first device to: determine a received signalstrength indicator (RSSI) of a first signal from a second device to athird device; determine, based on the RSSI exceeding a sensitivitythreshold of the third device, a transmission power level; and causesending of a second signal using the transmission power level.
 11. Thefirst device of claim 10, wherein the instructions, that when executed,cause the first device to cause the sending of the second signalcomprise instructions that cause the first device to cause the sendingof the second signal to a fourth device.
 12. The first device of claim10, wherein the instructions that, when executed, cause the first deviceto cause the sending of the second signal comprise instructions thatcause the first device to send the second signal using the transmissionpower level.
 13. The first device of claim 10, wherein the instructions,that when executed, cause the first device to determine the RSSI of thefirst signal comprise instructions that cause the first device toreceive an indication of the RSSI of the first signal.
 14. The firstdevice of claim 10, wherein the instructions, that when executed, causethe first device to determine the RSSI of the first signal compriseinstructions that cause the first device to: receive, by the firstdevice, the first signal; and determine, based on the received firstsignal, the RSSI of the first signal.
 15. The first device of claim 10,wherein the instructions, that when executed, cause the first device tocause the sending of the second signal comprise instructions that causethe first device to send, to at least one of the second device or thethird device, an indication to send the second signal using thetransmission power level.
 16. A non-transitory computer-readable mediumstoring instructions that, when executed, cause: determining a receivedsignal strength indicator (RSSI) of a first signal from a first deviceto a second device; determining, based on the RSSI exceeding asensitivity threshold of the second device, a transmission power level;and causing sending of a second signal using the transmission powerlevel.
 17. The non-transitory computer-readable medium of claim 16,wherein the causing sending of the second signal comprises causingsending of the second signal by a transmitter of at least one of thefirst device or the second device.
 18. The non-transitorycomputer-readable medium of claim 16, wherein at least one of the firstdevice or the second device comprises a premises device.
 19. Thenon-transitory computer-readable medium of claim 16, wherein thesensitivity threshold of the first device comprises a minimum signalstrength that the second device is configured to receive plus a bufferamount.
 20. The non-transitory computer-readable medium of claim 16,wherein the causing sending of the second signal using the transmissionpower level comprises causing sending, to at least one of the firstdevice or the second device, of data configured to modify a transmissionpower of the at least one of the first device or the second device. 21.A method comprising: determining a received signal strength indicator(RSSI) of a first signal received by a first device from a seconddevice; determining, based on the RSSI exceeding a sensitivity thresholdof the first device, a transmission power level; and causing the seconddevice to send a second signal using the transmission power level. 22.The method of claim 21, wherein the causing the second device to sendthe second signal using the transmission power level comprises sending,to a third device, information configured to cause the second device tosend the second signal using the transmission power level.
 23. Themethod of claim 21, wherein the causing the second device to send thesecond signal using the transmission power level comprises sending, tothe second device, an indication of the transmission power level. 24.The method of claim 21, wherein the causing the second device to sendthe second signal using the transmission power level comprises sending,to the second device, information configured to cause the second deviceto send the second signal using the transmission power level.
 25. Afirst device comprising: one or more processors; and memory storinginstructions that, when executed by the one or more processors, causethe first device to: determine a received signal strength indicator(RSSI) of a first signal received by the first device from a seconddevice; determine, based on the RSSI exceeding a sensitivity thresholdof the first device, a transmission power level; and cause the seconddevice to send a second signal using the transmission power level. 26.The first device of claim 25, wherein the instructions, that whenexecuted, cause the first device to cause the second device to send thesecond signal using the transmission power level comprise instructionsthat cause the first device to send, to a third device, an indication tocause the send device to send the second signal using the transmissionpower level.
 27. The first device of claim 25, wherein the instructions,that when executed, cause the first device to cause the second device tosend the second signal using the transmission power level compriseinstructions that cause the first device to send, to the second device,a third signal using the transmission power level.
 28. The first deviceof claim 25, wherein the instructions, that when executed, cause thefirst device to cause the second device to send the second signal usingthe transmission power level comprise instructions that cause the firstdevice to send, to a third device, an indication of the transmissionpower level.